- Aventri

www.BeckwithElectric.com

1

• Before joining Beckwith Electric, performed in Application, Sales and Marketing Management capacities at PowerSecure, General Electric, Siemens Power T&D and Alstom T&D.

• Provides strategies, training and mentoring to Beckwith Electric personnel in Sales, Marketing, Creative Technical Solutions and Engineering.

• Key contributor to product ideation and holds a leadership role in the development of course structure and presentation materials for annual and regional protection & control Seminars.

• Senior Member of IEEE, serving as a Main Committee Member of the Power System Relaying and Control Committee for over 25 years.

• Chair Emeritus of the IEEE PSRCC Rotating Machinery Subcommittee (’07‐’10).

• Contributed to numerous IEEE Standards, Guides, Reports, Tutorials and Transactions, delivered Tutorials IEEE Conferences, and authored and presented numerous technical papers at key industry conferences.

• Contributed to McGraw‐Hill's “Standard Handbook of Power Plant Engineering.”

Wayne HartmannSenior VP, Customer Excellence

Beckwith Electric’s top strategist for delivering innovative technology messages to the Electric Power Industry through technical forums and industry standard development.

Speaker [email protected]

904-238-3844

Acronyms• CAPC = Capacitor Control (6280A, 6283A)

• REGC = Regulator Control (6200A)

• LTCC = Load Tapchanging Transformer Control (2001D)

• FPF = Forward Power Flow

• RPF = Reverse Power Flow

• DA = Distribution Automation

• OLTC = On Load Tapchanger (REG and PWR XFRM)

• DMS = Distribution Management System

• EOL = End of Line, as in EOL Voltage

• Reconfig = System Reconfiguration

• FLISR= Fault Location, Isolation, System Recovery

2

2

2

Objectives [1]

Discuss Impact of DA on VVO

Sample DA Scenarios

Explore IEEE 1547‐2018• Active VAr control of DER

1547 and Impact on Distribution Protection• Bidirectional Load and Fault Currents• Effects on Reclosers and Feeder Relaying

Control of Watts and VAr in DER

3

3

Objectives [2] Reverse Power Flow (FFP) and Importance of Source Strength Determination

• Use of OLTC Autodetermination of Source Strength in OLTCs

RFP OLTC Strategies

Review of LDC and other Fundamental OLTC Settings

4

4

3

Objectives [3]

Smart Voltage Reduction

Use of VAR Bias (instead of LDC) for Better OLTC and Line Cap Coordination

Use of VAr Bias for DER CVR and Improved CVRf

Use Autoadaptive Line Capacitor Control to Cope with DA

Putting it All Together: Optimization Tactics

5

5

VVO Concepts

What is VVO?How do you obtain it?

What do you get out of it?

6

6

4

VVO Adjusting system voltage and pf by properly

controlling OLTC and reactive assets. Ideally:

OLTC Assets used for Voltage Issues due to Real Power Changes

• Load Tapchanging Transformer Controls (Substation)

• Voltage Regulator Controls (Substation and Line)

Reactive Assets used for VAR regulation (loss minimization)

Reactive Assets for Voltage Issues due to ReactivePower Changes

• Capacitors (Line)

• Active VAR Regulating DER (new)

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7

VVO Results Reduced lossesXC counters XL of lines

Decreased operation of OLTC elements

Deferred capital expenditures and improved capital asset utilization

Reduced electricity generation and environmental impacts

Flatter voltage profileAllows better CVR without low voltage violation at the end‐

of‐line

8

8

5

126

120

114

1 2 3 4 5 6 7 8

Vo

lts

(s

ec

on

da

ry)

25% of Feeder Length

50% of Feeder Load

Sub

stat

ion

Loads only

Voltage Profile

No VVO

9

126

120

114

1 2 3 4 5 6 7 8

Vo

lts

(s

ec

on

da

ry)


50% of Feeder Load

Sub

stat

ion

Loads only

Voltage Profile

No VVO

CAPS ON

Capacitors decrease losses proving flatter voltage profile10

6

VVO Controllers LTC Controls (Load Tapchanger) (M‐2001D)

Applied on LTC Transformers in Substations

Control voltage

Regulator Controls (6200A)

Applied on Regulators

Substation and Line

Control voltage

Capacitor Controls (6280A, 1; 6283A, 3) Applied on Pole Top Capacitor Banks

Provide VARs and influence voltage

We’ll explore some advanced applications

Advanced Volt/VAR Optimization Controllers = ADVVOC11

Traditional Methods: Control BasedOLTC Elements

OLTCs use line drop compensation (LDC) to cope with line losses (R/XL, Z)

Only as good as line model

May not coordinate with downline capacitors for VAR/pf

regulation

OLTCs use line drop compensation to cope with line losses (XL)

Only as good as line model

May not coordinate with downline capacitors for VAR/pf

regulation

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12

7

Line Drop Compensation Principle

Peak Loading

Light Loading

Distance

Voltage

LoadCenter

Without LDC

RegulatedBus

13

Line Drop Compensation Principle

Distance

Voltage

Light Loading

Peak Loading

LoadCenter

With LDC

RegulatedBus

14

8

• Regulates voltage at a point closer to the load as voltage drops due to loss in the line because of line impedance and current

Without LDC at full Load

With LDC at full Load and unity power factor(R=5)

120V118V 115V

125V123V 120V

LDC – R,X

15

LDC ‐ Z

Application: Distribution bus regulation

Concept: Increase bus voltage as the load level increases

No individual line information

Uses current magnitude ONLY

BUS

DistributionFeeders

200 ma(CT)

VSet

00 I

V

16

9

Vo

ltag

e A

dd

ed t

o B

and

cen

ter

01005010 150

Load Current – Full Load at 200mA

5

10

15

20

25

200

2V

5V

10V

15V

LDC Graph

Should use high voltage block for 1st

house protection!!!

Forward Power and LDC

17

Caps use “feedforward” control such as time‐of‐day, day, temperature, seasonality

Feedforward is only as good as your assumptions and

correlation factors

Caps use voltage or VAR w/voltage override

Difficult to coordinate with OLTC elements using LDC with

voltage or VAR w/voltage override

VAR controls not much good near end of line

Little load flow

VAR controls must be on main line

Voltage controls may be on line tap when “real estate” is sparse

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18

Traditional Methods: Control BasedReactive Support Elements

10

Costly: Can run millions of dollars $$$$$

Is DMS everywhere on a Utility’s system?

Requires system model

Expensive to create (needs GIS and live system inputs)

Expensive and time intensive to maintain

Requires model dynamic update and near real‐time communications to system and system elements

Traditional Methods: DMS‐Comms Based

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Data quality impacts load flow model results

Tap position data requirements for model

Multiple substation and feeder configurations need to be reflected in the model

Need a DAC regardless if communications between DMS‐SCADA‐DACs fail

Traditional Methods: DMS‐Comms Based

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11

Same CAPEX and OPEX as DMS‐Comms Based

Need an ADVVOC if communications between DMS‐SCADA‐ADVVOCs fail

May use less comms bandwidth by employing profile changes and setpoint changes versus “micromanagement” control

Traditional Methods: Hybrid DMS‐Comms to Control Based

21

DA and DER Impact on VVO

DA (DMS) can reconfigure feeders Powerflows and levels change, resulting in voltage changes Placement of VVO equipment changes compounding the issue

DER is proliferating Powerflows and levels change, resulting in voltage changes Placement of DER can change due to DA 1547‐2018 allows reactive as well as active powerflow output, compounding the problem

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12

Sample DA Scenarios

What does DA do to power flow and source strength on line sections?

23

23

24

Volt/VAR Control Considerations from DA

7952 79

7952 79

79

• Normal open loop

• Uses recloses to perform FLISR

• V/VAR feeder devices employed: REGC and CAPC

24

13

25


X

• Fault occurs on feeder

25

26


• Fault is cleared by 52 (O/C trip and LO) and 79 (27)

• Tie 79 closes (uses H/D logic)

• Power is restored to most of loop system

• Reverse power flow occurs on some section of the newly-configured feeder

26

14

27

Voltage Control Considerations from DA: REGC

How to address RFP:

1. Do nothing (does not work; REG LDC causes operational errors)

2. Use communications to control by setpoint or setting group

3. Use change of powerflow direction to change to a new predeterminedcontrol mode

4. Use change of powerflow direction and source strength (by REGC measurement) to initiate autodetermination of best control mode

27

Reverse Power Flow

How do VVO elements act after source strength and power flow direction changes?

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28

15

RPF: Why We Care????

• With high penetration levels of DA and/or DER on the distribution system it is becoming more common to have the voltage regulators deal with reverse power situations

• The solution to the OLTC problem gets complicated as the control needs to know (or assume) the source of reverse power.

• It is important to select the correct reverse power mode of operation for voltage regulators otherwise dangerous high or low voltage levels may result causing equipment damage or misoperations

2929

Forward PowerReverse Power

Vo

ltag

e

-100-50-100 50

Percent of Full Load Current

-5

0

5

10

15

100

2V

5V

10V

15V

LDC Graph

Notice that if the current is reverse, LDC drops the voltage instead of raising it

Forward Power and LDC

30

16

Issues with DA and DER

Reverse Power Flow (RPF)

Both a reconfig and DER may cause RPF

With DER (weaker source than system), forward regulation should be employed

With reconfig (strong source switches), reverse regulation should be employed

How do we know weak and strong source

if you have mix of DA and DER?

31

The Reverse Power Flow (RPF) Problem

• It’s all about source strength

– If the source is weak, small impact (most DER)

– If the source is strong, big impact (reconfiguration)

• Impacts of strong source RPF:

– Drives LDC the wrong way

– Regulation should be in the now reverse direction

• The tail cannot wag the dog

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32

17

No RPF Source

33

OLTCXFRM‐1

OLTCREG‐1

79/152/1

Forward Powerflow

Load Load Load Load

Weak RPF Source

34

OLTCXFRM‐1

OLTCREG‐1

79/152/1

DER DER

Forward Powerflow without DER

Reverse Powerflowwith DER

Load Load Load Load

18

No RPF Source: Open Loop

35

OLTCXFRM‐1

Load Load Load Load

OLTCXFRM‐1

OLTCREG‐3

Load Load Load Load

Load

Load

Load

Load

OLTCREG‐1

52/1 79/1

79/5

79/2

52/2 79/3 79/4

Forward Powerflow without Reconfig

OLTCREG‐2

OLTCREG‐4




Strong FPF Source: Reconfig

36

19

Strong RPF Source: Reconfig

37

OLTCXFRM‐1

Load Load Load Load

OLTCXFRM‐1

OLTCREG‐3

Load Load Load Load

Load

Load

Load

Load

OLTCREG‐1

52/1

52/2 79/3 79/4


OLTCREG‐2

OLTCREG‐4


OLTCREG‐5

79/5

79/279/1

Dead Section

Reverse Powerflowwith Reconfig



How Can One Know About Source Strength

• Guess it, assume it

• Cheap and easy if one can make assumptions or guess

• LTC or REG makes RPF determination and goes into predetermined response mode, either:

• No DER on line, and the only way you can have RFP is a reconfiguration with a new source direction (assume new strong source)

• No reconfiguration possible, so only DER can cause RPF

38

20

How Can One Know About Source Strength

• Use Communications

• DMS uses information gathered about system elements and configuration

– DMS determines best control action selection

– Requires DMS and radios or other comms media

– Expensive and complex

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40

Communications to REGC

1. REGC is able to provide detailed power system information to DMS/DA such as operationaldata (ex., V, A, W, S, demand, THD, open/closed status) and, and non‐operational informationsuch as asset maintenance information, detailed PQ monitoring and event information (DNP)

2. DMS/DA, per modeling or feedback control, sends analog value DNP setpoints to REGCs fornew control action. REGCs perform per new setpoints.

3. DMS/DA, per modeling or feedback control, sends DNP profile change command to REGC fornew control action. REGC performs per new setting profile. This takes less communicationbandwidth and frequency than Solution 1.

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21

Communications to REGC/LTCC

• Pros:– REGC does as commanded, using analog setpoint or profile group

• Using “Heartbeat,” control knows if communications is lost– Go to “Plan B;” operation mode with comms

• Cons:– Costs of communications infrastructure– Requires DMS with either modeling or feedback to properly execute commands

• Feedback requires recloser and switch position status, EOL voltage sensing

• Modeling requires creation, updating and upkeep

41

41

Use of Powerflow Direction Change by REGC/LTCC

• Pros:

– Communications not needed to detect RPF situation

– Control is autonomous (no DMS/SCADA required)

– Autodetermination Mode allows dynamic source stiffness determination and proper regulation based on the dynamic conditions

• Cons:

– Settings may require adjustment if feeder changes over time

• Ex.: LDC‐R, XL

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42

22

Knowing Relative Source Strength is KEY

• Use “Autodetermination”– Reverse Power Flow Source Strength Determination

• Control determines relative source strength

– Why it is important• Weak source (DER) results in continuing forward regulation

– May employ different LDC or VAR‐Bias settings

• Strong source (Reconfig) results in use of reverse regulation

– May employ different Bandcenter, Bandwidth, and LDC or VAR‐Bias settings

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43

VT1 = 100% - X1. ( ) (1)

VT2 = 100% + X2. ( ) (2)ΔV = 0.625% for one tap change

Initial condition: LTC neutral tap position, Source 1 and 2 voltages are each 100%, no reactive current flow (unity power factor)

Simulation of LTC Transformer/Regulatorwith Two sources: Simplified Model

4444

23

Case #

DPI1 DPI2

Reactive Current (IX)

Through the transformer

VT1 VT2 V

1 2% ∞ 0 100% 100.625% .625

2 ∞ 2% 0 99.375% 100% .625

3 2% 20% 1.953 % 99.96 % 100.4% .04

4 20% 2% 1.953 % 99.6 % 100.035% .04

5 2% 2% 7.14 % 99.85% 100.14% .29

Simulation Results

4545

1 & 2: System reconfiguration; one source, radial

3 & 4: DER (weak) vs. System (strong)

5: Two weak sources

When RPF is detected, operation is set initially to “DG Mode”

V is measured for two tap operations:

V = VMBT -VMAT

where VMBT = measured load side voltage just before a tap change VMAT = measured load side voltage one second after the tap change

Autodetermination of Source Strength with RPF

46

No

rma

lly

ex

pe

ct

0.6

25

V p

er

tap • If the measured V is > 0.47 (75%) of the

normal expected value (0.625V) for two consecutive tap changes, Autodetermination will maintain “DG Mode” operation

• If the measured V is <= 0.31V (50%) of the normal expected value (0.625V) for two consecutive tap changes, Autodetermination changes to “Regulate Reverse Mode” operation

V≥ 75%

0.625V 50 < V < 75%

V ≤ 50%

24

47

Reverse Power Source Strength Determination:

User Manually Designates

“DG Mode”

Reverse Power Flow Detected

User Manually Designates

Source Strength

“Regulate Reverse”

Weak Strong

47

48

Reverse Power Source Strength Determination:

Autodetermination

48

25

REGC/LTCC: Autodetermination of Operating Mode with Reverse Power

49

49

REGC/LTCC: Autodetermination of Operating Mode with Reverse Power

Once RPF is detected, checks source strength Makes two taps and checks for satisfactory voltage change

If voltage change is less than 50% of 0.625V, assumes strong source from

RPF direction, uses “Regulate Reverse”

If voltage change is greater than 75% of 0.625V, assumes weak source from

RPF direction, uses “DG Mode”

50

50

V= 75%

0.62

5V 50 < V< 75%

V = 50%‐1

Uses “Forward Power”Band Center, Band Width

and Time

Distributed Generation

121.0

4

+2

+5

Reverse Power

45

FPF

RPF

RPF Source StrongRPF Source Weak

Autodetermination:Senses Reverse Powerflow (RPF), then: If normal load side remains weak source,

switches to “DG Mode” If normal load side changes to strong

source, switches to “Regulate Reverse” (Reverse Power)

120.0

+1

+3

4

Forward Power

26

Terminology Cross Reference

51

Use of Powerflow Direction Change by REGC/LTCC

REGC/LTCC: Reverse Power Method Discussion

RPF Selection

52

27

REGC/LTCC: Reverse Power Method Discussion• Return to Neutral – drives tap position to neutral and then stops

– Use where small unpredictable change in voltage may be encountered on RPF side of REG

– “Feel safe” strategy when one cannot distinguish the source strength of the RFP

– Is it DER, and possible weak?– Is it DA, and strong?

– Can be risky as there is no control once at the neutral tap– The only control action possible is to have is force lower limit (runback) if

voltage becomes too high

• Block – inhibits automatic operation, leaving regulator on present tap– Use where source of RPF is not expected to change voltage on RPF side of

REG– Also a “feel safe” strategy when one cannot distinguish the source strength of

the RFP.– Is it DER, and possible weak?– Is it DA, and strong?

– Can be risky as there is no control and the voltage begins to deviate

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53


• “Return to Neutral”

• Operates to neutral position and then freezes there

54

28


• “Block”

• Freezes on present tap

• No control

55


• Regulate Forward (Ignore) – continues control action as though forward power flow continued to exist. – Use where weak DER, without active voltage control, is causing RPF

– Uses same settings with normal forward power flow

• Regulate Forward (DG Mode) ‐ This mode of operation is the same as the Ignore mode, plus provides ability to change line drop compensation (LDC)– Use where DER power output is large enough to warrant new LDC settings A separate set of LDC settings can be specified which will be applied during reverse power

• This can include LDC factor magnitudes, signs and the use of R and XL , or Z

• VAR‐Bias may also be selected

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56

29

REGC/LTCC: Forward Power

• “Regulate Forward”

• Use for normal forward load

• May use with very weak sources (weak DER only), or when you need to drive down voltage due to DER causing a voltage rise

57

LDC Graph

• Regulating forward, +LDC raises bandcenter as FPF becomes larger• Regulating forward, -LCD lowers bandcenter as FPF becomes larger

REGC/LTCC:Regulate Forward

Load(FPF)

Source(FPF)

Source(RPF)

Load(RPF)

FPF

Regulates FPF Side

OLTCXFRM‐1

OLTCREG‐1

79/152/1

DER DER

Forward Powerflow(w‐wo DER)

Load Load Load Load

[Volts added to Bandcenter]

[Volts subtracted from Bandcenter]

FPFRPF

(+) LDC R/XL

or Z

(‐) LDC R/XL

or Z

+V

‐V

30

REGC/LTCC: Reverse Power, “DG Mode”

• DG Mode for “Distributed Generation” and “Distributed Energy Resource”

• Regulates forward with new LDC values (magnitude and sign)

• Use with weak source (DER)

59

LDC Graph

• Regulating forward, -LDC raises bandcenter as RPF becomes larger• Regulating forward, +LCD lowers bandcenter as RPF becomes larger

REGC/LTCC:“DG Mode”

Load(FPF)

Source(FPF)

Source(RPF)

Load(RPF)

RPF

Regulates FPF Side



(‐) LDC R/XL

or Z

FPF

+V

‐V

(+) LDC R/XL

or Z

31

REGC/LTCC: Reverse Power, “Regulate Reverse”• Regulate Reverse (Calculated): Voltage Sensing: With RPF, control uses tap position knowledge and FPF side voltage

Regulates according to reverse power settings– Use where RPF source to REG is a stronger source– Regulate voltage on the RPF side of the REG

• Typically used for reconfiguration

• Regulate Reverse (Measured): Voltage Sensing: With RFP, control switches its voltage sensing input to a RPF side VT

– RFP side VT must be available

Regulates according to reverse power settings– Use where RPF source to REG is a stronger source– Regulate voltage on the RPF side of the REG

• Typically use for reconfiguration

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61

RPF

Source(RPF)

Load(RPF)

Load(FPF)

Source(FPF)

REGC/LTCC: Reverse Power, “Regulate Reverse”

• “Regulate Reverse” Calculated

• Regulates reverse with new voltage settings and LDC values

• Use with strong RPF source (reconfig)

• Uses tap position and calculates voltage on previous source side of regulator

• No additional VT needed

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32

REGC/LTCC: Reverse Power, “Regulate Reverse”

• “Regulate Reverse” Measured

• Regulates reverse with new voltage setpointsand LDC values

• Use with strong RPF source (reconfig)

• Uses additional VT on previous supply side of regulator

63

LDC Graph

REGC/LTCC: “Regulate Reverse”

• Regulating reverse, +LCD raisesbandcenter as RPF becomes larger

• Regulating reverse, -LDC lowersbandcenter as RFP becomes larger

OLTCXFRM‐1

Load Load Load Load

OLTCXFRM‐1

OLTCREG‐3

Load Load Load Load

Load

Load

Load

Load

OLTCREG‐1

52/1

52/2 79/3 79/4


OLTCREG‐2

OLTCREG‐4

OLTCREG‐5

79/5

79/279/1

Dead Section




N.O. Tie


33

VVO/CVR Concepts

What is VVO?What is CVR?

How to Optimize Both

65

65

VVO and CVR ‐ Why

• Lowering distribution voltage levels during peakperiods to achieve peak demand reductions

• Reducing voltage levels for longer periods to achieve electricity conservation

• Reducing energy losses in the electric distribution system

Benefits include deferral of capital expenditures, energy savings, and greater operational flexibility

and efficiency

Voltage and Reactive Power Management – Initial Results: US DOE, 12/12

34

Conservation Voltage Reduction• Conservation Voltage Reduction (CVR)

– Part of Voltage/VAr Optimization (VVO)

– Intentional lowering of distribution circuit voltage within the lower band of the allowed ANSI C84.1 (2006)

• Standard for Electric Power Systems and Equipment – Voltage Ratings

• Range A is the optimal voltage range • Range B is acceptable, but not optimal

Voltage Reduction

Conservation Voltage Reduction Goal of voltage reduction is to reduce load

V= I * R for resistive loadThe lower the V the lower the IThe lower the I, the lower the I2R = W (constant Z load)

Ex., incandescent lights, strip heatersNot true if load is not constant power type (constant PQ load):

Ex., motors, power supplies

Can be deployed at: All times For load reduction periods (peak reduction) During system emergencies when the voltage is collapsing due

reactive load exceeding available supply

% VR pf 1.0 pf 0.9Load Reduction Load Reduction

2 % 1.5 % 0.5%

4 % 3.0 % 2.0%

EPRI “Distribution Green Circuits” Report ‐ 2010

35

Load Models and CVR Factor• Load models

– Constant Power (PQ)– Constant Impedance (Z)– Constant Current (I)

Load current changes inversely to the change in voltage

Load current changes linearly with the change in delivered voltage, and the demand varies as a squared function of the voltage change (ex., incandescent bulb)

Power delivered to the load varies linearly with the change in voltage delivered to the load

Evaluating Conservation Voltage Reduction with WindMil® ‐ Milsoft

CVRf = P/V

0.8 to 1 is typical

Greater than 1 is really good

Constant Power (PQ or kVA)

Constant Impedance (Z) Constant Current (I)

Motors (at rated load) Incandescent Lighting Welding Units Power Supplies Resistive (Strip) Water Heaters Electroplating

Fluorescent Lighting Electric StovesWashing Machines Clothes Dryers

Load Models and CVR Factor

Evaluating Conservation Voltage Reduction with WindMil® ‐ Milsoft

CVRf = P/V

0.8 to 1 is typical

Greater than 1 is really good

Constant Power (PQ or kVA)

Constant Impedance (Z) Constant Current (I)

Motors (at rated load) Incandescent Lighting Welding Units Power Supplies Resistive (Strip) Water Heaters Electroplating

Fluorescent Lighting Electric StovesWashing Machines Clothes Dryers

36

126

120

114

1 2 3 4 5 6 7 8

Vo

lts

(s

ec

on

da

ry)


50% of Feeder Load

Sub

stat

ion

Loads only

Voltage Profile

No VVO

126

120

114

1 2 3 4 5 6 7 8

Vo

lts

(s

ec

on

da

ry)


50% of Feeder Load

Sub

stat

ion

Loads only

Voltage Profile

No VVO

CAPS ON

Capacitors decrease losses proving flatter voltage profile

37

126

120

114

1 2 3 4 5 6 7 8

Vo

lts

(s

ec

on

da

ry)


50% of Feeder Load

Sub

stat

ion

Voltage Profile

Loads onlyNo VVO

CAPS ON


VVO

126

120

114

1 2 3 4 5 6 7 8

Vo

lts

(s

ec

on

da

ry)


50% of Feeder Load

Sub

stat

ion

Voltage Profile

Loads onlyNo VVO

CAPS ON


VVO

VVO + CVR

38

Smart Voltage ReductionGet the Voltage Reduction Called For –Do you think you always get it????

75

75

Here is how to get it

Voltage Reduction of the Past

Load Reduction called with Load Management Software

Load Reduction Software » SCADA »Output Relay » LTC/Regulator Input

Output relays connected to auxiliary summing transformer with multiple taps

Auxiliary summing transformer has taps connected/disconnected by control relays to create a highersensing voltage the LTC or Regulator Control

This higher voltage, sensed by the LTC/Regulator Control, would now cause the control to issue tap-down commands to lowervoltage

The control would not know that it is in voltage reduction mode, and would simply react to the sensed voltage change

Historical Voltage ReductionLINE

VT

SUMMINGTRANSFORMER

SCADACONTACTS

FOR VOLTAGE REDUCTION

LTCCONTROL

39

Voltage Reduction of the Past

Historical Voltage Reduction -Disadvantages

The time delay to tap is still in play

The percentage of reduction is fixed due to the taps on the summing transformer

Each percentage reduction point required an auxiliary relay

If the communications failed while in reduction, the LTC or Regulator would remain in voltage reduction

Voltage Reduction

Voltage Reduction in Modern Controls

Controls typically support three reduction levels

Reduction level range set from 1 -10 %

• Typical for static or digital controls:Contact sensing inputs

The contacts would be from a SCADA RTU and/or local switches

• For digital controls, additionally:Using the integrated HMI on the control (buttons)

Using PC software locally

Using SCADA interface (ex., DNP from RTU)

Using Ethernet by radio (ex., DNP TCP/IP)

Using Cellular or other medium

40

Voltage Reduction External Connections

Contacts Used for Voltage ReductionDigital Voltage Regulator Control

Voltage Reduction Example

Voltage Reduction in Modern Controls

Voltage Reduction changes the bandcenter to induce the controls to lower the voltage instead of increasing the sensed voltage

Signal to control can be:o SCADA to contacts, contacts to controlo Direct SCADA DNP write to control

Time delay skipped on initial voltage reduction command

Because the bandcenter is being altered, entering reduction does not always reduce the voltage, or reduce near the amount of requested reduction

41


Voltage ReductionBandcenter set to 122V, Bandwidth of 3V

Apply a 2% reduction122 – 122* 0.98 = 119.56 or 119.6

Upper rail = 119.6 + (3/2) = 121.1Lower rail = 119.6 – (3/2) = 118.1

123.5

122.0

120.5

Before Reduction

121.1

119.6

118.1

After Reduction

Assume 0.75V/tap (10V/16 taps = 0.75V/tap) 120.7V before reduction, after reduction that value is still in-band Results in no voltage reduction, 0%

3

3120.7

120.7


Voltage Reduction

Bandcenter set to 122V, Bandwidth of 3V

Apply a 3% reduction of122 – 122* 0.97 = 118.34 or 118.3

Upper rail = 118.34 + (3/2) = 119.8 Lower rail = 118.34 – (3/2) = 116.8

123.5

122.0

120.5

Before Reduction

119.8

118.3

116.8

After Reduction

Assume 0.75V/tap (120*10%=12V; 12V/16 taps = 0.75V/tap) 120.7V before reduction, 2 Taps Down Taken Tap 1 = 119.95, Tap 2 = 119.2 % = ( | V1 - V2 | / ((V1 + V2)/2) ) * 100 = ( | 120.7 - 119.2 | / ((120.7 + 119.2)/2) ) * 100 = 1.25% reduction

120.7

119.95 119.23

3

42


Voltage ReductionBandcenter set to 122V, Bandwidth of 3V

Apply a 4% reduction of122 – 122* 0.96 = 117.12 or 117.1

Upper rail = 117.1 + (3/2) = 118.6 Lower rail = 117.1 – (3/2) = 115.6

123.5

122.0

120.5

Before Reduction

118.6

117.1

115.6After Reduction

Assume 0.75V/tap (120*10%=12V; 12V/16 taps = 0.75V/tap) 120.7V before reduction, 3 Taps Down Taken Tap 1 = 119.95, Tap 2 = 119.2, tap 3 = 118.45 % = ( | V1 - V2 | / ((V1 + V2)/2) ) * 100 = ( | 120.7 - 118.45 | / ((120.7 + 118.45)/2) ) * 100 = 1.88% reduction

120.7

119.95 119.23

3

118.45

Voltage ReductionVoltage Reduction – Present Method

If the goal of voltage reduction is to reduce voltage, we want to finish the reduction on the lower end of the band, not the higher end

Previous example: 3% request, 1.25% delivered

123.5

122.0

120.5

Before Reduction

119.8

118.3

116.8

After Reduction

120.7

119.95 119.23

3

43

Voltage Reduction

Smart Voltage ReductionApply a 3% reduction of

122 – 122* 0.97 = 118.34 or 118.3Upper rail = 118.34 + (3/2) = 119.8Lower rail = 118.34 – (3/2) = 116.8

123.5

122.0

120.5

Before Reduction

119.8

118.3

116.8

After Reduction

120.7

119.95119.23

3

118.4

117.7

Temporarily:• Disable Upper Band Limit • Use Bandcenter as Upper Band Limit

Assume 0.75V/tap (120*10%=12V; 12V/16 taps = 0.75V/tap) 120.7V before reduction, 4 Taps Down Taken Tap 1 = 119.95, Tap 2 = 119.2, Tap 3 = 118.4, Tap 4 = 117.7 % = ( | V1 - V2 | / ((V1 + V2)/2) ) * 100 = ( | 120.7 - 117.7 | / ((120.7 + 117.7)/2) ) * 100 = 2.52% reduction

Voltage Reduction

Leaving Voltage Reduction - Present Method

This may not be a high enough voltage to cause voltage controlled capacitors to switch off

123.5

122.0

120.5

During Reduction

119.8

118.3

116.8

Normal Operation

120.7

119.95119.2

3

3

44

Leaving Voltage Reduction – Present MethodUnintended Results: Cap Banks May Stay On Too Long

REDUCTION kV NORMAL kV TEST MVAr NORMAL MVAr

Typically when entering reduction, all switched capacitors will close as the voltage is reduced (assumed voltage control)

This may cause circuits to be leading when in reduction

When leaving reduction, some of the capacitors need to be switched off to get back to unity power factor

Voltage Reduction

Leaving Voltage Reduction:

Smart Voltage Reduction Method

The extra voltage will now allow the capacitors to start timing to an open

The lower band is temporarily disabled to force the voltage to finish between the bandcenter and the high band edge

Once the voltage crosses the bandcenter, the lower band edge becomes active again

123.5

122.0

120.5

During Reduction

119.8

118.3

116.8

Normal Operation

120.7

119.95119.2

3

3

122.2121.5

45

Cap Banks Opening After Leaving ReductionSmart Voltage Reduction Employed

Voltage Reduction


Voltage Reduction: Block Lower

123.5

122.0

120.5

Before Reduction

118.6

117.1

115.6

After Reduction

120.7

119.95 119.23

3

118.45

• A “Block Lower” setting of 118 will stop the control from performing voltage reduction if low limit setpoint is violated

• Be sure the “Block Lower” setting does not interfere with voltage reduction settings

Block Lower

46

Voltage Reduction

Voltage Reduction Turnoff Timer

Used to turn off Voltage Reduction (VR) if entered via SCADA or pulsed contacts

Intent is to remove voltage reduction mode if SCADA is lost and communications goes down

Control will automatically remove VR once the timer expires, even if SCADA is still communicating

o New signal during timing interval would keep VR going

Voltage Reduction

Voltage Reduction - Summary

o The control will never reduce the actual voltage by the percentage requested

o The larger the bandwidth, the less actual reductiono The “Block Lower” setting:

Does not block voltage reduction

Does block a tap down command from occurring if the measure voltage is less than setpoint

o There is no time delay when entering or exiting voltage reduction

47

Annex: Percent Calculations

Voltage Reduction: New ApplicationDER Hosting Improvement

• With high penetration of DER, perfect XL/XCcompensation still leaves R

• Heavy power flows from DER back to feeder source cause voltage rise on feeder– Exasperated at near the end of the feeder as R to the source increases

• High voltage rise can minimize hosting ability• Concept: Drop voltage at the feeder original to have a wider voltage rise band along feeder to the end of the line

94

48

Voltage Reduction: Increase DER Hosting Ability

• At times of high feeder DER output, enter voltage reduction– Voltage at head end lowers

– Voltage at end of line lowers

• DER picks up voltage from end of line back to head end

• Use either negative LDC or positive VAR‐Bias– Negative LDC lowers voltage bandcenter as reverser power flow increases

– Positive VAR‐Bias discussed later section

95

LDC Graph



Load(FPF)

Source(FPF)

Source(RPF)

Load(RPF)

RPF

Regulates FPF Side



(‐) LDC R/XL

or Z

FPF

+V

‐V

(+) LDC R/XL

or Z

96

49

LDC Graph

Loads Loads Loads Loads

Loads Loads Loads

LTC REG

1pu

0.95pu

0.95pu

Power Floww

Distance

Line Drop Compensation (LDC)

LDC Graph

50

LDC Graph


Loads Loads

LTC REG

1pu

0.95pu

0.95pu

Power Floww

Distance

Line Rise Compensation (LRC)

DERDER

LoadsDERDER

Use of VAR Bias (instead of LDC)

for Better OLTC and Line Cap Coordination

Using LDC to Coordinate can be less than optimal

VAR‐Bias as a new concept to unify VVO with OLTCs and CAPs

100

100

51

Improved Volt/VAR Coordination between DERs/CAPCs and REGCs/LTCCs

• REGCs and/or LTCCs:

– Typically use LDC‐RX or LDC‐Z

– No direct feedback mechanism using LDC‐RX or LDC‐Z for PF or VAR control

• Voltage‐control based CAPCs:

– VAR measurement not available

– Switch on voltage• Less expensive than VAR control and sensors

• May be used at end of line

How do we coordinate to obtain optimum VVO/IVVC?

101

101

Use of VAR‐Bias to Coordinate DERs/CAPs with REGs and LTCs

• REGC and LTCC use information on VAR flow

– Is the VAR flow out to the line (load)?

– Is the VAR flow into the source?

• The above indicate if you are or are not at/near unity power factor

• VAR flow into the REG or LTC indicate the voltage downline is higher than the voltage at the REG or LTC

102

102

52

CAP Voltage Control

103

103

Setting with Deadband

Deadband avoids hunting


• Use a “VAR‐Bias” characteristic to change the response of the REGC or LTCC

• The VAR‐Bias characteristic can be tailored for normal operation (non‐CVR) and CVR operation

– Normal (non‐CVR) Operation: Negative VAR Bias

– CVR Operation: Positive VAR Bias

104

104

53

Use of VAR Bias in OLTC Devices (instead of LDC)

• Use VAR‐Bias control to modify behavior of the voltage adjustment with regard to real and reactive power flows to properly manipulate voltage bandcenter

Normal, Non-CVR ApplicationNegative Linear VAR Bias

Lagging VARs (+)

120V

118V

116V

122V

124V

Leading VARs (‐)

105

VAR Bias (LTCC and REGC)• In the Negative Mode (Normal), as:

– VARs flow toward source (leading VAR at LTCC/REGC)• Voltage bandcenter rises, allowing line voltage to rise, causing voltage‐controlled CAPCs to switch banks off, stopping VAR output and lowering line voltage

– VARs flow toward load (lagging VAR at LTCC/REGC)• Voltage bandcenter lowers, allowing line voltage to drop, causing voltage‐controlled CAPCs to switch banks on, outputting VAR, and raising line voltage

106

This action creates unity power factor and flattens the voltage profile

The OLTC device does nottake a tap

106

54

VAR‐Bias: Near or at Unity PF

107


Lagging VARs (+)

120V

118V

116V

122V

124V

Leading VARs (‐)

OLTCTap Down

OLTCTap Up

VAR‐Bias: Bandcenter Decreases with Lagging VAR


Lagging VARs (+)

120V

118V

116V

122V

124V

Leading VARs (‐)

NO Tap Command

As voltage falls:CAPs switch ONDER exports VAr Voltage rises from increase in VAr

108

55

VAR‐Bias: Bandcenter Increases with Leading VAR


Lagging VARs (+)

120V

118V

116V

122V

124V

Leading VARs (‐)

NO Tap Command

As voltage rises:CAPs switch OFFDER absorbs VAr Voltage lowers from decrease in VAr

109

Normal Operation:Negative VAR‐Bias

• Voltage near center of band

• Near unity power factor

110

110


Leading VARsLagging VARs120V

121V

118V

117V

116V

122V

123V

124V

119V (‐)

(+)

56


• Inductive load increases, pf lags, voltage decreases.

• REG bandcenter lowers.

• Caps come on• Voltage and VAR

normalize

111

52

Closed

Opened

Closed

Opened

Closed

Opened

Closed

Opened

121V

118V

117V

116V

122V

123V

124V

119V

120V

NORMAL OPERATION (non‐CVR)

1

2

3

111


• Inductive load decreases, pf leads, voltage rises.

• REG bandcenter rises.

• Caps switch off• Voltage and VAR normalize

112

52

Closed

Opened

Closed

Opened

Closed

Opened

Closed

Opened

121V

118V

117V

116V

122V

123V

124V

119V

120V


1

2

3

112

57


• Resistive load decreases, pf remains the same, voltage rises

• REG taps down, voltage normalizes

• CAPs do not change VAR output

113

52

Closed

Opened

Closed

Opened

Closed

Opened

Closed

Opened

121V

118V

117V

116V

122V

123V

124V

119V

120V


1

2

3

113


• Resistive load increases, pf leads, voltage decreases

• REG taps up, voltage normalizes

• CAPs do not change VAR output

114

52

Closed

Opened

Closed

Opened

Closed

Opened

Closed

Opened

121V

118V

117V

116V

122V

123V

124V

119V

120V


1

23

114

58

Voltage Bandcenter and Bandwidth: LTC/REG, CAP, DER

• CAPS furthest away from source have shorter time delay than upline CAPs

115

115

Normal, Non - CVR ApplicationNegative Linear VAR Bias


121V

118V

117V

116V

122V

123V

124V

119V

REG

CAP

REG

CAP

(+) (‐)

Voltage Settings and Timings: LTC/REG, CAP, DER

• CAPS furthest away from source have shorter time delay than upline CAPS

• REGs use VAR‐Bias with larger bandwidth and longer time delays than CAPs

116

116

59

VAR-Bias and Deep CVR How low can you go?Lower than you may think!

117

117

CVR Operation:Positive VAR‐Bias

118

• REG forces voltage lower

• CAPs begin to switch on and DER outputs VAR

118


121V

118V

117V

116V

122V

123V

124V

119V

CVR ApplicationPositive Linear VAR Bias

1

2 (‐)(+)

60


119

• VARs begin to lead.

• REG forces voltage even lower.

• More CAPs switch on and DER outputs VAR

119

Volts (secondary)

CVR: REGs/LTC with DERs/CAPs

• For CVR, forcing overVAr on feeder causes end of line voltage to rise

• You can have a deeper voltage reduction at the beginning of the line where most of the load is located (EPRI Green Circuits)

120

120

61

The cost is ADVVOCs, which you need anyway

No extensive comms system

NO DMS required

Feedback loop from CAPs to OLTCs is made from VAR flow/direction

VAR‐BiasTake Away

121

DER Impact on VVO

DER is proliferating Powerflows and levels change, resulting in voltage changes

Placement of DER can change due to DA

IEEE 1547‐2018, allows reactive as well as active powerflow output, compounding the problem

122

122

62

• If large amounts of DER are easily “shaken off” for transient out‐of‐section faults, voltage and power flow upset can occur in:

– Feeders

– Substations

– Transmission

• Fault ride‐through capability makes the system more stable

– Distribution: Having large amounts of DER “shaken off” for transient events suddenly upsets loadflow and attendant voltage drops.

• Impacts include unnecessary LTC, regulator and capacitor control switching

• If amount of DER shaken off is large enough, voltage limits may be violated

– Transmission: Having large amounts of DER “shaken off” for transient events may upset loadflow into transmission impacting voltage, VAR flow and stability

IEEE 1547-2018

123

123

1547‐2018: Active Voltage/VAR Control

• Coordination with and approval of, the area EPS and DR operators, shall be required for the DR to actively participate to regulate the voltage by changes of real and reactive power.

• The DR shall not cause the Area EPS service voltage at other Local EPSs to go outside the requirements of ANSI C84.1‐2006 1 1995, Range A.

124

124

63

Fault Ride-Through Categories I, II, III

• Category I: based on essential bulk electric system (BES) stability/reliability needs and reasonably attainable by all DER technologies that are in common usage today

• Category II: covers all BES stability/reliability needs and coordinated with existing reliability standards to avoid tripping for a wider range of faults

• Category III: based on both BES stability/reliability and distribution system reliability/power quality needs and coordinated with existing interconnection requirements for very high DER penetration

IEEE 1547-2018

125

125

126

FIDVR EventFault Induced Delayed Voltage Recovery

• Power system event in which the voltage remains at low levels for several seconds after a transmission, sub‐transmission, or distribution fault has been cleared

• FIDVR is caused by stalling of induction motors driving constant torque loads 126

64

127

FIDVR EventFault Induced Delayed Voltage Recovery

• Power system event in which the voltage remains at low levels for several seconds after a transmission, sub‐transmission, or distribution fault has been cleared

• FIDVR is caused by stalling of induction motors driving constant torque loads 127

Voltage Trip Limits: CAT I

128

IEEE 1547-2018

128

65

129

IEEE 1547-2018

Voltage Trip Limits: CAT I

129

Voltage Trip Limits: CAT II

130

IEEE 1547-2018

130

66

131

IEEE 1547-2018Voltage Trip Limits: CAT II

131

Voltage Trip Limits: CAT III

132

IEEE 1547-2018

IEEE 1547-D6.0

132

67

133

IEEE 1547-2018

Voltage Trip Limits: CAT III

IEEE 1547-D6.0 133

Voltage Regulation PerformanceReactive Power Capability Categories A, B

• Category A Covers minimum performance capabilities needed for Area

EPS voltage regulation that are reasonably attainable by all state-of-the-art DER technologies

Performance is deemed adequate for applications where the DER penetration in the distribution system is lower, and where the DER power output is not subject to frequent large variations

IEEE 1547-2018

134

134

68

Voltage Regulation PerformanceReactive Power Capability Categories A, B

• Category B

• Covers all requirements within Category A and specifies supplemental capabilities needed to adequately integrate the DER in local Area EPS where the DER penetration is higher or where the DER power output is subject to frequent large variations.

IEEE 1547-2018

135

135

IEEE 1547-2018

136

136

CAT1

CAT2

CAT3

CATA

CATB

RIDE-THROUGHVOLTAGE REGULATION

&REACTIVE POWER CAPABILITY

PERFORMANCE‐BASED CATEGORY APPROACH

DERSUPPLIERS

AUTHORITYHAVING

JURISTRICTION(AHJ)

Recommended:• Use CATS I and A together• Use CATS II, III and B together

69

DER Interconnection Relay as the Utility Interface Point

137

137

Example of Inverter P & Q Output Capability

Graph from Mar/Apr 2014 IEEE PES Magazine Article “Lab Tests” by Roland Brundlinger, Thomas Straaser, Georg Lauss, Andy Hoke, Sudipta Chakraborty, Greg Martin, Benjamin Kropotkin, Jay Johnson and Eric de Jong

138

138

70

Inverter Control Modes

Constant Power factor mode (adjustable)

Reactive power mode (adjustable)

Voltage‐reactive power (Volt‐VAr) mode

Active power‐reactive power mode (Watt‐VAr)

Volt‐active power (Volt‐Watt)

139

139

IEEE 1547-2018

140140

DER Actively Controlling VAR

Constant pf Constant VAR

71

• Why? As voltage rises, counter with absorbing VAR• Uses droop characteristic• Based on power and voltage sensing at PCC • If inverter based, a “Smart” Inverter

141

DER Actively Controlling VARVolt‐VAr

141

IEEE 1547-D6.0

• Why? As real power output increases, counter voltage rise by absorbing VAR

• Uses droop characteristic• Based on power and voltage sensing at PCC • If inverter based, a “Smart” Inverter

142

DER Actively Controlling VARWatt‐VAr

142

IEEE 1547-D6.0

72

• Why? As real power output increases, area voltage can increase due to line losses (R and XL)

• Uses droop characteristic• Based on power and voltage sensing at PCC • If inverter based, a “Smart” Inverter

143

DER Actively Controlling VARVolt‐Watt

143

IEEE 1547-D6.0

CAPs and DER• As power flows and assumed reactive voltage drops can

change as DER proliferates, consider changing fixed CAPs to switched to avoid overvoltage (from excessive VAR support) under high DER output conditions

• Consider active voltage (VAR) control of DER as proliferation increases

144

144

73

Use of VAR Bias (instead of LDC)

for Better OLTC and Line Cap Coordination

Using LDC to Coordinate can be less than optimal

VAR‐Bias as a new concept to unify VVO with OLTCs and CAPs

145

145

Improved Volt/VAR Coordination between DERs/CAPCs and REGCs/LTCCs

• REGCs and/or LTCCs:

– Typically use LDC‐RX or LDC‐Z

– No direct feedback mechanism using LDC‐RX or LDC‐Z for PF or VAR control

• Voltage‐control based CAPCs:

– VAR measurement not available

– Switch on voltage• Less expensive than VAR control and sensors

• May be used at end of line

How do we coordinate to obtain optimum VVO/IVVC?

146

146

74


• REGC and LTCC use information on VAR flow

– Is the flow out to the line (load)?

– Is the flow into the source?

• The above indicate if you are or are not at/near unity power factor

• VAR flow into the REG or LTC indicate the voltage downline is higher than the voltage at the REG or LTC

147

147

CAPs and DER• As power flows and assumed reactive voltage drops can

change as DER proliferates, consider changing fixed CAPs to switched to avoid overvoltage (from excessive VAR support) under high DER output conditions

• Consider active voltage (VAR) control of DER as proliferation increases

148

148

75


• Use a “VAR‐Bias” characteristic to change the response of the REGC or LTCC

• The VAR‐Bias characteristic can be tailored for normal operation (non‐CVR) and CVR operation

– Normal (non‐CVR) Operation: Negative VAR Bias

– CVR Operation: Positive VAR Bias

149

149

VAR Bias (LTCC and REGC)• In the Negative Mode (Normal), as:

– VARs flow toward source (leading VAR at LTCC/REGC)• Voltage bandcenter rises, causing voltage‐controlled:

DERs to decrease VAR output

CAPCs to switch banks off, stopping VAR output

– VARs flow toward load (lagging VAR at LTCC/REGC)• Voltage bandcenter lowers, causing voltage‐controlled:

DERs to decrease VAR output

CAPCs to switch banks on, outputting VAR

150

This action tends to create unity power factor and flatten voltage profile

150

76

VAR Bias (LTCC and RECC)• In the Positive Mode (CVR), as:

151

This action tends to allow deep voltage reduction at the feeder origin as end of line voltage is higher than at REG or LTC output


121V

118V

117V

116V

122V

123V

124V

119V


(‐)

(+)

151

• VARs flow toward source (leading VAR at LTCC/REGC)

– Voltage bandcenter lowers, causing voltage‐controlled:DERs to decrease VAR output

CAPCs to switch banks on, outputting VAR

• VARs flow toward load (lagging VAR at LTCC/REGC)

– Voltage bandcenter rises, causing voltage‐controlled:DERs to decrease VAR output

CAPCs to switch banks off, stopping VAR output


• Voltage near center of band


152

152



121V

118V

117V

116V

122V

123V

124V

119V (‐)

(+)

77


• Inductive load increases, pf lags, voltage decreases.

• REG bandcenter lowers.

• Caps come on, DER outputs VAr

• Voltage and VArnormalize

153

52

Closed

Opened

Closed

Opened

Closed

Opened

Closed

Opened

121V

118V

117V

116V

122V

123V

124V

119V

120V


DERVArOUT

VArIN

VLOW VHIGH

DERVArOUT

VArIN

VLOW VHIGH

1

2

3

153


• Inductive load decreases, pfleads, voltage rises.

• REG bandcenter rises.

• Caps switch off, DER consumes VAr

• Voltage and VArnormalize

154

52

Closed

Opened

Closed

Opened

Closed

Opened

Closed

Opened

121V

118V

117V

116V

122V

123V

124V

119V

120V


DERVArOUT

VArIN

VLOW VHIGH

DERVArOUT

VArIN

VLOW VHIGH

1

2

3

154

78


• Resistive load decreases, pfremains the same, voltage rises

• REG taps down, voltage normalizes

• CAPs and DER do not change VAr output

155

52

Closed

Opened

Closed

Opened

Closed

Opened

Closed

Opened

121V

118V

117V

116V

122V

123V

124V

119V

120V


1

2

3

DERVArOUT

VArIN

VLOW VHIGH

DERVArOUT

VArIN

VLOW VHIGH

155


• Resistive load increases, pf leads, voltage decreases

• REG taps up, voltage normalizes

• CAPs and DER do not change VAroutput

156

52

Closed

Opened

Closed

Opened

Closed

Opened

Closed

Opened

121V

118V

117V

116V

122V

123V

124V

119V

120V


1

23

DERVArOUT

VArIN

VLOW VHIGH

DERVArOUT

VArIN

VLOW VHIGH

156

79

Voltage Bandcenter and Bandwidth: LTC/REG, CAP, DER

• CAPS and DER furthest away from source have shorter time delay than upline similar devices

• This examples uses CAPs before DER

– Assuming DER charges for reactive support

157

157



121V

118V

117V

116V

122V

123V

124V

119V

REG

CAPDER

REG

CAP

DER

(+) (‐)

Voltage Settings and Timings: LTC/REG, CAP, DER

• CAPS and DER furthest away from source have shorter time delay than upline similar devices

• This examples uses CAPs switching before DER, assuming DER charges for reactive support

• REGs use VAR‐Bias with larger bandwidth and longer time delays than CAPs or DER

158

158



121V

118V

117V

116V

122V

123V

124V

119V

REG

CAPDER

REG

CAP

DER

80

Before CVR Operation:Negative VAR‐Bias

• Normal load, voltage near center bandcenter


159

159

VAR-Bias and Deep CVR

How low can you go? Lower than you may think!

160

160

81


161


• CAPs begin to switch on and DER outputs VAr

161


121V

118V

117V

116V

122V

123V

124V

119V


1

2 (‐)

(+)


162



• More CAPs switch on and DER outputs VAr

162

82

Volts (secondary)


• For CVR, forcing overVAr on feeder causes end of line voltage to rise


163

163





• Use either negative LDC or positive VAR‐Bias– Negative LDC lowers voltage bandcenter as reverser power flow increases

– Positive VAR‐Bias discussed later section

164

83


165


• CAPs begin to switch on and DER outputs VAr

165


121V

118V

117V

116V

122V

123V

124V

119V


1

2 (‐)

(+)


166



• More CAPs switch on and DER outputs VAr

166

84

Volts (secondary)


• For CVR or DER Hosting VR, forcing overVAr on feeder causes end‐of‐line voltage to rise


167

167





• Use either negative LDC or positive VAR‐Bias– Negative LDC lowers voltage bandcenter as reverse power flow increases

– Positive VAR‐Bias plus negative LDC lowers voltage as either/both reverse real and reactive power flow increase

168

85

LDC Graph



Load(FPF)

Source(FPF)

Source(RPF)

Load(RPF)

RPF

Regulates FPF Side



(‐) LDC R/XL

or Z

FPF

+V

‐V

(+) LDC R/XL

or Z

169

LDC Graph


Loads Loads Loads

LTC REG

1pu

0.95pu

1.05pu

Power Floww

Distance

Line Drop Compensation (LDC)

86

LDC Graph

LDC Graph


Loads Loads

LTC REG

1pu

0.95pu

1.05pu

Power Floww

Distance

Line Rise Compensation (LRC)

DERDER

LoadsDERDER

172

Maximizing DER Hosting with Voltage Constraint

LTC/REG LRC Control Action

87

173

173

Maximizing DER Hosting with Voltage Constraint

DER Voltage Droops

1

1.03

1.06

0.970.94

Voltage (pu)

Reactive Power

Absorb

Emit

1 1.03

Voltage (pu)

Active Power

1.06

1 pu

0 pu

1.05

1.05

Effects of Reverse Power from DER on Line Drop Compensation (LDC)

If RPF is large enough to cause reverse power flow, the REGC will operate to lower voltage

Using to “DG Mode” allows change to the polarity of the LDC (and factors if desired) under reverse power conditions to prevent this from occurring

174

174

Normal LDC with FPF Improper LDC with RPF

88

Vol

tage

Vol

tag

e

Effect of DER on RegulatorLine Drop Compensation (LDC)

LDC is reduced when DER contributes power

More DER power = less load = less LDC = voltage setpoint lowers

If DER is in PF mode, it maintains a VAR output to not import or export any VARs, so it cannot control voltage

Voltage profile can change depending on:o R and XL of the lineo Reactive compensation to

counter the XL

o Power output of the DER

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Vol

tag

e


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176

Assume line R and XL drops are low

Assume REGC in DG Mode Assume variable DER

power output per the graphic

Line voltage assumes “smile” profile

Curve of smile (flat or very arced) not the severeo Arc more severe with

higher R and XL, more DER output

89


177

177

Vol

tag

e

Assume line R and XL drops are low

Assume REGC in DG Mode Assume variable DER

power output per the graphic

Line voltage assumes “smile” profile

Curve of smile (flat or very arced) Arc more severe with

higher R and XL, more DER output

Use of an End-of-Line Monitor (EOL) toTransmit Voltage Value to Regulator

With EOL feedback, you are not modeling the EOL voltage. You measure it.

EOL monitoring, working with a regulator, can handle dynamic situations and multiple sources to adjust line voltage

Works when DG Mode where unfavorable line/DER output characteristics existo “Smile arc” too severe or DER EOL voltage too high

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178

Go to Slide 39 / Page 19

90

Line Caps and DA

How do we get proper VAr support after a reconfiguration?

179

179

180

Volt/VAR Control Considerations from DA: CAPC

How to address reconfiguration:

1. Do nothing (resulting control may be suboptimal)

2. Use communications to control by setpoint or setting group

3. Use autoadaptive methodology to retune switch timing per relative position on newly configured feeder

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91

181

Communications to CAPC

1. CAPC is able to provide detailed power system information to DMS/DA such as operationaldata (ex., V, A, W, S, demand, THD, open/closed status) and, and non‐operational informationsuch as asset maintenance information, detailed PQ monitoring and event information (DNP)

2. DMS/DA, per modeling or feedback control, sends analog value DNP setpoints to CAPCs fornew control action. CAPCs perform per new setpoints.

3. DMS/DA, per modeling or feedback control, sends DNP profile change command to CAPC fornew control action. CAPC performs per new setting profile. This takes less communicationbandwidth and frequency than Solution 1.

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Communications to CAPC

• Pros:– CAPC does as commanded, using analog setpointor profile group

• Using “Heartbeat,” control knows if communications is lost– Go to “Plan B;” operation mode with comms

• Cons:– Costs of communications infrastructure– Requires DMS with either modeling or feedback to properly execute commands

• Feedback requires recloser position status, EOL voltage sensing; may require VAR sensing at substation

• Modeling requires creation, updating and upkeep

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92

Use of Autoadaptive Methodology by CAPC

• CAPCs, using Autoadaptive V based control, alter their timing to properly switch per control’s (new) location from source on feeder (furthest from source switches on first, off last).

– This implementation maintains better multi‐capacitor control action on a given feeder regardless of configuration

– Uses V observed on switching to change timing. Example:• Vfactor = 90 sec. / 1 volt = 90 sec/V.

• Sec. = Vfactor / V (MEASURED)

• Increasing V(MEASURED) = further distance (more impedance) from source

• Decreasing V (MEASURED) = closer distance (less impedance) from source

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184

90 sec. 45 sec. 90 sec.45 sec.

V = 1 V = 2 V = 2 V = 1

Distance Downline (Increasing Z)

V V

V factor = 90 sec. / 1 volt = 90 sec/V.

Sec. = Vfactor / V

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185

90 sec. 30 sec. 45 sec. 90 sec.

V = 1 V = 3 V = 2 V = 1

Distance Downline (Increasing Z)

V V

V factor = 90 sec. / 1 volt = 90 sec/V.

Sec. = Vfactor / V


• Pros:

– Communications not needed to retune CAPC time settings

– Control is autonomous (no DMS/SCADA required)

– Upon another reconfiguration, CAPC will learn new time setting depending on its position form the source

• Cons:

– None

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94

Putting it All Together:Optimization Tactics

Adapting to DA and DER to Optimize VVO/CVR

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187

Time Delay

Definite Time

188

95

Time Delay

Definite Time

189

Inverse Time Characteristic

190

96

Inverse TD Example

Example

Bandcenter = 120 V

Bandwidth = 2 V

Inverse Time Delay = 120 V

Sensed Voltage = 123 V

Time Delay Factor = (Vsense - Vbandcenter)/(BW/2)

Time Delay Factor =(123-120)/(2/2) = 3/1 = 3

From Graph, % Factor = 34%

Time = Setting * % Factor

Time = 120 sec. * 0.34 = 40.8 = 41 sec. 191

When to Use Inverse Time1. When voltage is just outside of band, regulating

device will wait a longer time before tapping which may reduce operations

• Asset preservation

2. When voltage undergoes a rapid excursion, regulating device will tap quickly to maintain voltage quality• Large load rejection (fault clearing, reconfig)• Large load pickup (restoration, reconfig)• DER VAR regulation issues (poor coordination with

Utility VVO assets)• DER power output issues (irradiance, unpredictability)

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Time Delay Reset• Two types of timers

– When voltage goes out of bandwidth and then returns to normal before tap is taken, there are two ways to reset the timer

1. Integrating:1. Increments timer 1 second voltage is out of range and

decrements timer 1 second when voltage is within range» Tends to allow tap change

2. Instantaneously:1. Increments timer 1 second every second voltage is out of

range and resets timer to zero immediately when voltage is within range» Tends to inhibit tap change 193

Consider use of reactive controlling DER• Compliment and fine tune LTCC, REGC and CAPC• Save LTC and REG operations

Consider substation caps be controlled on VAR/pf with high voltage and low voltage override

Consider line caps use CAPC that employ voltage measurement

Consider REGCs using Autodetermination for selection of RFP control mode

194

VVO Elements

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VVO Elements

• Use of VAR‐Bias avoids LDC issues as DER power output increases

• If DER can control VAR output, coordinating DER voltage output setting with REGC/LTCC bandcenter will keep voltage at the setting

– VAR‐Bias reacts to VAR to maintain unity PF

– REGC/LTCC, CAPs and active DERs maintain voltage

– If DERs charge for reactive support, use CAPs first

• Employ narrower bandwidth on CAPs

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Extended Capabilities of Advanced Volt/VAR Distribution Automation

Controllers (ADVVOCs) for Data Acquisition and Use Into

Higher Power SCADA/DMS Applications

99

Our ExplorationADVVOCS & DMS for Enhanced:

1) Asset Maintenance

Push unsolicited messages to SCADA/DMS regarding asset health of controlled elements

Allow drill down to logging for additional information

2) System Monitoring

Push unsolicited messages on high THD% to monitor effects of DER, caps and resonance

Allow drill down to individual harmonic levels for precise analysis

197

Our ExplorationADVVOCS & DMS for Enhanced:

3) Distributed IntelligencePerform min/max calculations for monthly updates

Eliminates need for constant polling, storage and data crunching in the DMS

Low bandwidth requirements and leased comms costs

4) Alarm, Limit and Runback FunctionsAlarms, Limit and Runback Functions to supervise DMS actions and issues beyond DMS immediate control

Eliminates need for the DMS to execute these functions, and also corrective action taken without latency

Low bandwidth requirements and leased comms costs

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Asset Maintenance:Feeder Capacitor Banks

Feeder Capacitor Banks Applied in distribution for VAR support Applied in distribution for voltage control Supplied VARs raise voltage and change pf VARs switched off lower voltage and change pf

Bank Construction Details Switches are used on each phase Fuses protected switches, banks and interconnected wiring form faults Some capacitor cans have fuses internal to component capacitors within cans (packs)

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Single Phase Sensing, Simultaneous Phase Switching Voltage sensed on one phase All phases switched on or off at one time May employ :

3‐single phase switches, or 1 ganged switch

Three phase sensing, independent phase switching Voltage sensed on all 3 phases

For switching decision, can sense each phase, can switch on highest, lowest or average

Phases may be switched independently or simultaneously Employs 3‐single phase switches

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101

Capacitor Bank Components

Oil SwitchVacuum Switch

Voltage Transformer Arrestor

Fuse

201

Credit: Cooper Power Systems

Capacitor Bank Components

Capacitor Cut‐Away of Capacitorw/Internal Fuses

202

Credit: Cooper Power Systems

102


Grounded Bank, 1 Voltage Sensing

CONT

ROL

CONT

ROL

203


Ungrounded Bank, 1 Voltage Sensing

A

B

C

CONT

ROL

A

B

C

CONT

ROL

T, C,“a” or “b”

T, C,“a” or “b”

2 2

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103


Switch or Switches Failure• Stuck open or stuck closed

Phase Fuses• Blown

Fuses for Packs in Cans• Blown

Connecting Wiring

• Open circuits

• Shorts (Fuse)

Arrestors• Shorts (Fuse)

Failure Modes

205


Failure FrequencyAt any given moment, over 30% of distribution feeder cap banks may have failuresOften only detected by feeder patrolling at time intervalsReactive support is compromised with bank failures Lack of VAR causing poor power factor

• May negatively impact CVR

OLTC elements may have to operate much more than they should with failed banks

• Becomes maintenance issue for OLTC elements206

104

Asset Maintenance:ADVVOC Failure Detection Methods

Alarm 1: Control Power Phase Open Indicates Bank Power Down

Alarm 2: Bank Failure Alarm Indicates Bad Fuse, Conductor or Switch

BANK FAILURE SCENARIO Fuse Blown, Open Connecting Wire, Open SwitchAssuming Battery Backup to Control

207

Failed Phase(s)

Alarm Action

Asset Maintenance:ADVVOC Failure Detection Methods

Alarm 3: Switch Fail to Open Detectable by monitoring switch auxiliary contacts, or, Detectable by examining open command against lack of

level neutral current Alarm 4: Switch Fail to Close Detectable by monitoring switch auxiliary contacts, or, Detectable by examining open command against low level

of level neutral current

BANK FAILURE SCENARIO Switch Failure to Close on Close Command Switch Failure to Open on Trip Command

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Treatment of Alarms at ADVVOC Push unsolicited messages to SCADA/DMS regarding

asset health of controlled elements Allow drill down to logging for additional information

209

Notes:1. Capacitor control may be 1‐ or 3‐phase sensing, voltage only

or voltage and current

System Monitoring:Feeder Capacitor Banks & Voltage Regulators

Feeder Capacitor Banks For monitoring, controls with three-phase

sensing may be applied Current monitoring dependent on if current is

sensed “Usual Suspects” available: V, I, W, VAR, S Capable of monitoring THD% voltage and

THD% current

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Line Voltage Regulators Applied in distribution for voltage regulation OLTC autotransformer used to tap to raise and

lower voltage For monitoring, controls sense voltage and

current Each regulator uses a control, therefore 3-phase

voltage and current measurement is available “Usual Suspects” available: V, I, W, VAR, S ADVVOCs capable of monitoring THD% voltage

and THD% current211


Distribution System Loads Load types have changed Proliferation of Electronic Loads Power Electronics

Variable Speed Drives DER (Inverter Based)

Switching Power Supplies for Lighting and Other Loads

Proliferation of Capacitors and Harmonic Filter Banks

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Rise in Harmonics Harmonics can interfere with operation of

sensitive loads Harmonics can overload transformers and

conductors Harmonics can raise motor heating Resonance can sometimes develop between

harmonic sources and capacitor/filter banks Harmonics are strongest at the source and

decrease as they travel through system impedances

• Strong sources absorb harmonics better than weak sources

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214

6 Pulse Converter ASD Harmonic Order

6 Pulse ConverterASD Harmonics

Credit: TMEICMedium Voltage Application School

108


215

Credit: Siemens WhitepaperHarmonics in Power Systems; Causes, Effects and Control


IEEE has Guidelines for Harmonic Levels IEEE 519, Recommended Practice and Requirements for

Harmonic Control in Electric Power Systems

216Credit: IEEE 519

109


IEEE has Guidelines for Harmonic Levels IEEE 519, Recommended Practice and Requirements for

Harmonic Control in Electric Power Systems

217Credit: IEEE 519


IEEE has Guidelines for Harmonic Levels IEEE 1547, Standard for Interconnection and Interoperability of

Distributed Energy Resources with Associated Electric Power Systems Interfaces

218Credit: IEEE 1547

110


If THD% limits as set are exceeded, push unsolicited alarm to SCADA/DMS

Once alarm received, an integrity poll can be made by DMS/SCADA and the harmonic levels (THD and individual harmonics) can be read.

Alternatives: If the communication infrastructure allows, a remote connection

can be made between the control using its software to examine THD and individual levels in CSV and graphic formats, or,

Connect to the control directly using its software to examine THD and individual levels in CSV and graphic formats

219


asset health of controlled elements Allow drill down for additional information

220


Notes:1. Each regulator employs a control2. Capacitor control may be 1‐ or 3‐phase sensing, voltage only or voltage and current

111

Distributed Intelligence:Voltage Regulators

Planners use information such as Energy and Demand:

221

• Current Demand• Watt Demand• VAR Demand• VA Demand

• W‐Hrs Forward• W‐Hrs Reverse• VAR‐Hrs Forward• VAR‐Hrs Reverse

One can use SCADA/DMS to constantly poll, or let the ADVVOC measure the quantities and calculate

SCADA/DMS polls once per month, obtains values SCADA/DMS resets all values to zero, and the ADVVOC

measure and calculates for the next and ensuing months Greatly decrease bandwidth and DMS programming

Instead of SCADA/DMS “micromanaging” the ADVOC to control the element, let the SCADA/DMS select setting profiles (setting groups) to match operational conditions

Examples: Normal Mode Voltage Reduction Mode for CVR Voltage Reduction Mode for DER Hosting DA Switching with new line/load characteristics

Greatly decrease bandwidth and DMS programming

222

Distributed Intelligence:Feeder Capacitor Banks & Voltage Regulators

112

Data Polling from ADVVOC Request data at widely separated intervals

Select Setting Profile to Match System Conditions Simple binary data command

223

Notes:1. Each regulator employs a control2. Capacitor control may be 1‐ or 3‐phase sensing, voltage only or voltage and current

Distributed Intelligence:Feeder Capacitor Banks & Voltage Regulators

Alarm, Limit and Runback Functions:Voltage Regulators

If a DMS model has an error, and erroneous command may be given to a ADVVOC, resulting in a voltage violation

If the system changes and the DSM does not have visibility, or the change cannot be quickly sensed due to communication latency, an voltage violation may occur Fast block load removal due to a fault Fast power output change in highly penetrated DER

• PV in local area with rapid cloud cover

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225


Weather data from Tampa, FL (9/14/18) Irradiance is rapidly fluctuating from 200-1000 W/M2;

11AM to 1PMWith significant PV DER penetration, those power

swings would manifest as rapid voltage changes.What happens if DMS model or polling feedback from

sensors is not quick enough? Use Alarms, Limits and Runback on the ADVVOCs

226


Fluctuating Voltage from Fluctuating Irradiance Regulators adjusted for DER Hosting with High DER Output

114

227


Fluctuating Voltage from Fluctuating Irradiance Sudden cloud cover resulting in loss of DER output DMS does not control before violation occurs


Alarm: Push unsolicited message to SCADA/DMS that the voltage is close to violating

Limit: Do not allow the control, on its own or from DMS command, to move voltage in eth direction of the violation

Runback: If voltage continues to move to violation, control issues tap command to move voltage away from violation

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asset health of controlled elements Allow drill down for additional information

229

System Monitoring:Voltage Regulators

Notes:1. Each regulator employs a control

Summary

ADVVOCs and DMS can work together to make a better combined system

In this exploration we shared application buckets where the combined ADVVOC and DMS : Providing asset maintenance functions Improving visibility to the power system Decreased communication bandwidth requirements Decreased programming in the DMS Improving final control action

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References

Electric Power Distribution, Automation, Protection and Control, CRC Press, J. Momoh, ISBN 978-0-8493-6835-6

Effect of Distribution Automation on Protective Relaying, 2012, IEEE PSRC Working Group Report

IEEE 1547, Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces

IEEE 519, Recommended Practice and Requirements for Harmonic Control in Electric Power Systems

231

References Smart Distribution: DA/DMS System and Integration

with DERs and Microgrids, IEEE PES General Meeting – 2018; J. McDonald, J. Han-PhD.

Electric Power Engineering Handbook, CRC Press, L.L. Grigsby, ISBN 0-8493-8578-4

M-6200A Voltage Regulator Control Instruction Book, Beckwith Electric

M-6280A Capacitor Control Instruction Book, Beckwith Electric

• (1-Phase Sensing, Ganged Switching)

M-6283A Capacitor Control Instruction Book, Beckwith Electric

• (3-Phase Sensing, Ganged or Independent Pole switching)

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Recommended Reading• IEEE 1547 Series of Standards for Interconnecting

Distributed Resources with Electric Power Systems, http://grouper.ieee.org/groups/scc21/

• IEEE 1547‐2017 (Draft 6.7)

• IEEE 1547a, 2014, Standard for Interconnecting Distributed Resources with Electric Power Systems, Addendum 1.

• Application of Automated Controls for Voltage and Reactive Power Management – Initial Results, US DOE, 12/2012

• Beckwith Electric Company, M‐2001D Loadtapchanger Control Instruction Book, Chapter 6, 2016.

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• “Smart Reverse Power Operating Mode for Distribution Voltage Regulators to Handle Distributed Generation along with Feeder Reconfiguration,” Dr. Murty V.V.S. Yalla. Presented at the PacWorld Conference, 2015.

• R. Bravo B. Yinger, P. Arons, "Fault Induced Delayed Voltage Recovery (FIDVR) Indicators," IEEE T&D, 2014

• Distribution Line Protection Practices Industry Survey Results, Dec. 2002, IEEE PSRC Working Group Report

• D. James, J. Kueck, " Commercial Building Motor Protection Response Report," US DOE, Pacific Northwest National Laboratory, 2015

234

Recommended Reading

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• Evaluating Conservation Voltage Reduction with WindMil, Milsoft, G. Shirek, 2011

• C37.230, IEEE Guide for Protective Relay Applications to Distribution Lines, IEEE Power System Relaying Committee, Second Edition, 2007

• 1547a and Rule 21, Smart Inverter Workshop, June 21, 2013, SCE

• Bob McFetridge, Barry Stephens, “Can a Grid Be Smart without Communications? A Look at IVVC Implementation: Georgia Power’s Distribution Efficiency Program.” Presented at the Clemson Power Systems Conference, 2013.

235

Recommended Reading

235

• Implementing VVO with DER Penetration, IEEE Innovative Smart Grid Technology (ISGT) Conference, Washington DC, 2017

• Chuck Whitaker, Jeff Newmiller, Michael Ropp, Benn Norris, “Renewable Systems Interconnection Study: Distributed Photovoltaic Systems Design and Technology Requirements,” Sandia National Labs, Dec. 2012.

• Turan Gonen, Electric Power Distribution Engineering,2008, pp. 398-404.

• On-Site Power Generation, by EGSA, ISBN# 0-9625949-4-6

• Effect of Distribution Automation on Protective Relaying, 2012, IEEE PSRCC Working Group Report

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Recommended Reading

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Documents

- Aventri